Biology 1108

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Lecture 22

• Biology 1108
• Chapter 42 Circulation

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Learning Objectives

• Discuss
• Why heart attack reduces heart function
• How body regulates blood flow
• Blood clot formation
• Identify
• Where low blood pressure occurs in a circuit
• Contrast
• Systolic and diastolic pressures

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Importance of Circulation

• Transports materials to all body cells
• Carries wastes away
• Very necessary if body is more than few cells
  thick

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2 Basic Types

• Circulatory systems can be
• Open
• Closed

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Open Circulation

• Blood vessels end in openings
• Organs bathed in blood
• Diffusion of wastes/materials happens by direct
  contact with blood
• Example insects, lobsters have open circulation

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Closed Circulation

• Blood is confined to vessels
• 3 basic kinds of vessels
• Arteries
• Veins
• Capillaries
• Diffusion of materials/wastes through capillary
  membranes
• Requires an additional liquid outside vessels
  interstitial fluid

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Blood Vessels Form Follows Function

• Arteries
• Veins
• Capillaries

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Arteries

• Move blood away from heart
• Must withstand higher pressures
• Consist of epithelium, smooth muscle, connective
  tissue

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Veins

• Move blood towards heart
• Have series of one-way valves
• In the legs, walking helps blood return to heart
• Consist of epithelium, valves, smooth muscle,
  connective tissue

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Capillaries

• Must accommodate diffusion
• Very small, thin-walled, numerous
• Consist of only epithelium, basement membrane

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Closed Circulation in Vertebrate Animals

• Two basic types
• Single circuit system
• Dual circuit system

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Single Circuit System

• Example fish
• Fish heart has 2 chambers
• Atrium (passively receives blood)
• Ventricle (actively pumps blood)
• Circuit repeated is heart to gills to body

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Disadvantage to Single Circuit

• Body gets only low pressure blood
• Why? Must pass through capillary bed in gills
• Small capillaries restrict pressure!

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Dual Circuit Circulation

• Example mammals
• Heart has 4 chambers
• 2 atria
• 2 ventricles
• Circuits are
• Pulmonary circuit heart to lungs
• Systemic heart to body

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Advantage to Dual Circuit

• Body cells can receive blood under high pressure
• Greater performance in burst activities

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7th Inning Stretch
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Human Circulatory System

• Identify, discuss function of each structure
• Dont rely on color picture!
• Exam will be b/w
• Red/blue doesnt identify arteries/veins!

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Sample Questions

• Which veins carry oxygenated blood?

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Sample Questions

• Which veins carry oxygenated blood?

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Sample Questions

• Which arteries carry deoxygenated blood?

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Sample Questions

• Which arteries carry deoxygenated blood?

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Sample Questions

• Which side of the heart carries deoxygenated
  blood?

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Sample Questions

• Which side of the heart carries deoxygenated
  blood?
• Dont be confused by this picture!

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Sample Questions

• In passing from the atrium to ventricle, which
  valve must the blood go through?

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Sample Questions

• In passing from the atrium to ventricle, which
  valve must the blood go through?

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Sample Questions

• What is this structure?

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Sample Questions

• The aorta

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Cardiac Cycle

• 3 parts
• Diastole
• Systole
• Ventricle contraction

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Diastole

• Heart is completely relaxed
• Blood flows into receiving chambers (atria)

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Systole

• Atria contract
• Ventricles fill with blood

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Ventricles Contract

• Blood propelled out of heart towards two places
• Lungs
• Body

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Heart Beat Coordination

• S/A node
• S/A Sino-atrial
• The natural pacemaker
• Initiates heart beat
• Signals atria to contract
• Located in right atrium
• A/V node
• Receives signal from S/A node
• Delays signal approx. 0.1 sec
• In the wall between ventricles
• Tells ventricles to contract

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More on Murmurs

• Occur when heart valves wont close properly
• Apparently, fairly common (especially in
  children), most are harmless
• Websites
• To read more about murmurs, go to Plainsense
  website
• To hear a murmur, go to www.openheartsurgery.com
  website

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Angina Pectoralis

• Frequent chest pain because of gradual blockage
• Often signals cardiovascular disease

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Heart Attack

• Occurs due to blockage of coronary arteries
• Death of cardiac muscle tissue
• Scar tissue forms during recovery
• This is not muscle
• Does not contract
• Loss of function

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Cardiac Education

• Over past 30 years, death rate from heart disease
  down 25
• Awareness of diet, exercise, medications

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Pressure Throughout System
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Measuring Blood Pressure

• Systolic Pressure
• 1st, higher number
• Produced by systole (remember what this is?)
• Diastolic Pressure
• 2nd, lower number
• Produced by resistance of vessels to blood flow

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Controlling Blood Flow

• Only 5 to 10 of capillaries open at any given
  time
• Smooth muscle controls in two ways
• Arteriole constriction sheet of muscle
  surrounding small artery contracts
• Precapillary sphincters little bands of muscle
  at the root of each capillary

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Arteriole Constriction
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Precapillary Sphincters
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Red Blood Cells

• Erythrocytes
• Produced in bone marrow
• Production increases when kidney produces
  erythropoietin

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Blood Clots

• Two sealants involved
• Platelets
• Fibrinogen

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Platelets

• These are tiny membrane bound bits of cytoplasm
• Float through circulatory system
• Stick together when broken vessel detected
• Sufficient for small clots

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Fibrinogen

• A plasma protein
• Adds structural integrity to big clots